1. Field of the Invention
The present invention relates to an apparatus and method for guiding an autonomous traveling vehicle which travels identifying its own positions based on positioning information sent from satellites.
2. Prior Art
Recently, autonomously traveling and working vehicles doing programmed works unmannedly have been put into practical use in various fields. Typical examples of such vehicles are lawn mowing vehicles used in golf courses, sports grounds, parks and other outdoor fields, cultivators, vehicles for dusting agricultural chemicals or fertilizer and vehicles for doing civil engineering works.
These autonomously traveling and working vehicles (hereinafter, referred to just autonomous vehicles) are autonomously operated using two techniques, one is a Global Positioning System (GPS) and the other is a dead reckoning navigation method. GPS is a technique for finding a vehicle position by radio waives received from positioning satellites and the dead reckoning navigation method is a technique for determining a current vehicle position based on a running direction detected by an earth magnetism sensor and a traveling distance detected by a wheel encoder.
However, GPS has positioning errors caused by the time difference between satellites and the radio receiver, orbital errors, delay of radio wave in ionized layer or in atmosphere, multipass and the like. Generally, it is said that GPS has positioning errors of several tens meters and even D-GPS having a higher positioning accuracy than GPS has errors of several centimeters to several meters.